The invention relates generally to transportation apparatus and more specifically to a trailer which is adaptable to receive both large planar sheets of material as well as more conventional loads.
One current architectural trend emphasizes the extensive of use of glass. The spaciousness, natural lighting and occasionally scenery provided by glass panels is diminished by interrupting supports and thus many designs require large uninterrupted or minimally interrupted periods of glass often as great as 12 by 20 feet and occasionally larger. Given the current emphasis on energy conservation, the glass panels are frequently of double wall construction having an insulating layer of air or a vacuum in the space between. Not only do such double thickness insulated glass panels weigh approximately twice as much as their single panel counterparts, but also they are substantially more fragile.
The capital investment in machinery capable of manufacturing such large glass panels, particularly those having double walls and an evacuated region therebetween, is of such a magnitude that they are typically manufactured in only a limited number of locations. Frequently, therefore, they must be transported over long distances to the building in which they will be utilized.
I have developed several patented designs for transporting such glass sheets or panels. U.S. Pat. No. 3,848,917 discloses a trailer having pivoted, extensible arms and longitudinal beams which restrain the glass sheets. Another one of my designs is taught in U.S. Pat. No. 4,037,870 which discloses a trailer having a rigid A-frame and a plurality of clamping devices for restraining the glass sheets against both transverse and longitudinal movement. U.S. Pat. No. 4,195,738 also teaches a trailer having a plurality of centrally disposed rigid A-frame members. Lateral and longitudinal restraints which utilize a special adjustable interconnecting member accommodate various sizes of glass sheets. My most recent design, disclosed in U.S. Pat. No. 4,385,856 illustrates another A-frame trailer design in which lateral restraint of the glass panels is achieved by readily adjustable cargo straps.
While the above-noted devices each represent significant improvements in planar material transport apparatus, their task-specific design poses one significant economic problem. As noted previously, such trailers will typically transport glass from a manufacturing facility to a building site. They seldom return with a load; not only because of the obvious reason that this type of cargo typically only flows from the nearest manufacturing site to a building site but also because the trailers are relatively ill-adapted to transporting other cargo. In such a situation, every trailer travels one half of each journey in an unloaded condition. For the operator of such vehicles, this situation has become increasingly costly as fuel, user fees and wages have continued to increase.